ABSTRACT
The diagnosis of drowning is one of the major challenges in forensic practice, especially when the corpse is in a state of decomposition. Novel indicators of drowning are desired in the field of forensic medicine. In the past decade, aquatic bacteria have attracted great attention from forensic experts because they can easily enter the blood circulation with drowning medium, and some of them can proliferate in the corpse. Recently, the advent of next-generation sequencing (NGS) has created new opportunities to efficiently analyze whole microbial communities and has catalyzed the development of forensic microbiology. We presumed that NGS could be a potential method for diagnosing drowning. In the present study, we verified this hypothesis by fundamental experiments in drowned and postmortem-submersed rat models. Our study revealed that detecting the bacterial communities with NGS and processing the data in a transparent way with unweighted UniFrac-based principal coordinates analysis (PCoA) could clearly discriminate the skin, lung, blood, and liver specimens of the drowning group and postmortem submersion group. Furthermore, the acquired information could be used to identify new cases. Taken together, these results suggest that we could build a microbial database of drowned and postmortem-submersed victims by NGS and subsequently use a bioinformatic method to diagnose drowning in future forensic practice.
Subject(s)
Aquatic Organisms/microbiology , Bacteria/classification , Drowning/diagnosis , Drowning/microbiology , Forensic Medicine/methods , High-Throughput Nucleotide Sequencing , Animals , Blood/microbiology , Disease Models, Animal , Liver/microbiology , Lung/microbiology , Male , Rats , Rats, Sprague-Dawley , Skin/microbiologyABSTRACT
AIMS: The beneficial effects of cannabinoid type 2 receptor (CB2R) activation have been verified in various tissue repair processes. Our recent study revealed CB2R activation promotes myogenesis partly through Nrf2 signaling in a mouse skeletal muscle ischemia-reperfusion (IR) injury model. Other relevant mechanisms need to be further elucidated. Macrophages orchestrate tissue regeneration mainly by changing their phenotype and function. The aim of this study was to investigate the role of CB2R in IR-induced skeletal muscle regeneration, focusing on its impact on macrophage polarization and the consequences on myogenesis. MAIN METHODS: The effects of CB2R on skeletal muscle regeneration, and the macrophage infiltration and M1/M2 polarization were tested with the IR injury model in wild type (WT) and CB2R knockout (CB2R-KO) mice. The effect of CB2R on peritoneal macrophage polarization, and its impact on the myoblasts differentiation was evaluated by co-culture experiments in vitro. KEY FINDINGS: The present study revealed the myofiber regeneration was hindered in the CB2R-KO mice. The infiltration of M1 macrophages and relevant markers' protein expression were enhanced in the CB2R-KO mice, while that of M2 macrophages was decreased compared with the WT mice. The in vitro studies further demonstrated that the absence of CB2R promoted M1 polarization while inhibited M2 polarization. The promoted M1 polarization and retarded M2 polarization in CB2R-KO macrophages hindered myoblasts differentiation. SIGNIFICANCE: Overall, these results suggested CB2R plays a beneficial effect on skeletal muscle regeneration partly by regulating macrophage M1/M2 polarization after IR injury in mice.
Subject(s)
Cell Polarity/physiology , Macrophages/physiology , Muscle, Skeletal/physiology , Receptor, Cannabinoid, CB2/deficiency , Regeneration/physiology , Reperfusion Injury/metabolism , Animals , Cells, Cultured , Coculture Techniques , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Muscle, Skeletal/blood supplyABSTRACT
AIMS: Cannabinoid type 2 (CB2) receptor activation has been shown to attenuate IRI in various organs. NF-E2-related factor (Nrf2) is an anti-oxidative factor that plays multiple roles in regulating cellular redox homeostasis and modulating cell proliferation and differentiation. The protective effects of CB2 receptor activation on skeletal muscle IRI and the underlying mechanism that involves Nrf2 signaling remain unknown. MAIN METHODS: We evaluated the in vivo effect of CB2 receptor activation by the CB2 receptor agonist AM1241 on IR-induced skeletal muscle damage and early myogenesis. We also assessed the effects of CB2 receptor activation on C2C12 myoblasts differentiation and H2O2-induced C2C12 myoblasts damage in vitro, with a focus on the mechanism of Nrf2 signaling. KEY FINDINGS: Our results showed that CB2 receptor activation reduced IR-induced histopathological lesions, edema, and oxidative stress 1â¯day post-injury and accelerated early myogenesis 4â¯days post-injury in mice. Nrf2 knockout mice that were treated with AM1241 exhibited deteriorative skeletal muscle oxidative damage and myogenesis. In vitro, pretreatment with AM1241 significantly increased the expression of Nrf2 and its nuclear translocation, attenuated the decrease in H2O2-induced C2C12 cell viability, and decreased reactive oxygen species generation and apoptosis. CB2 receptor activation also significantly enhanced C2C12 myoblasts differentiation, which was impaired by silencing Nrf2. SIGNIFICANCE: Overall, CB2 receptor activation protected skeletal muscle against IRI by ameliorating oxidative damage and promoting early skeletal muscle myogenesis, which was partly via Nrf2 signaling.
Subject(s)
Muscle, Skeletal/drug effects , Receptor, Cannabinoid, CB2/physiology , Reperfusion Injury/prevention & control , Animals , Antioxidants/pharmacology , Apoptosis/drug effects , Cannabinoids/pharmacology , Cell Survival/drug effects , Heme Oxygenase-1/metabolism , Hydrogen Peroxide/metabolism , Male , Mice , Mice, Inbred C57BL , Muscle Development/drug effects , Muscle, Skeletal/physiology , Myoblasts/metabolism , NF-E2-Related Factor 2/drug effects , NF-E2-Related Factor 2/physiology , Oxidation-Reduction , Oxidative Stress/drug effects , Reactive Oxygen Species/metabolism , Receptor, Cannabinoid, CB2/agonists , Receptor, Cannabinoid, CB2/metabolism , Receptors, Cannabinoid/physiology , Reperfusion Injury/metabolism , Signal TransductionABSTRACT
HIPK2 is an evolutionarily conserved serine/threonine kinase and is considered a co-regulator of an increasing number of transcription factors modulating a variety of cellular processes, including inflammation, proliferation and fibrosis. Skeletal muscle injuries repair is an overlapping event between inflammation and tissue repair. There are no reports about HIPK2 expression in skeletal muscles after trauma. A foundational study on distribution and time-dependent expression of HIPK2 was performed by immunohistochemical staining, Western blotting and quantitative real-time PCR, which is expected to obtain a preliminary insight into the functions of HIPK2 during the repair of contused skeletal muscle in mice. An animal model of skeletal muscle contusion was established in 50 C57B6/L male mice. Samples were taken at 1, 3, 5, 7, 9, 14, 17, 21 and 28 days after contusion, respectively (5 mice at each posttraumatic interval). 5 mice were employed as control. No HIPK2-positive staining was detected in uninjured skeletal muscle. Intensive immunoreactivties of HIPK2 were observed in polymorphonuclear cells, round-shaped mononuclear cells, regenerated multinucleated myotubes and spindle-shaped fibroblastic cells in the contused tissue. The HIPK2-positive cells were identified as neutrophils, macrophages and myofibroblasts by double immunofluorescent procedure. HIPK2 protein and mRNA expression were remarkably up-regulated after contusion by Western blotting and qPCR analysis. The results demonstrated that the expression of HIPK2 is distributed in certain cell types and is time-dependently expressed in skeletal muscle after contusion, which suggested that HIPK2 may participate in the whole process of skeletal muscle wound healing, including inflammatory response, muscle regeneration and fibrogenesis.
